Christian frederik iiilkier



(No Model.)

0. P. HILKIER.

THERMOSTAT.

No. 403,937. Patented May 28, 1889.

w/msss; jflwgr INVENTOR.

. v BY ATTOHIVEYJ.

UNITED STATES PATENT OEEIcE.

(.lllllfl'llAN FREDERIK lllliKlER, OF COPENHAGEN, Dl lblillAllh'.

TH ERMOSTAT.

SPECIFICATION forming part of Letters Patent No. 403,937, dated May 28,1889.

Application filed December 29, 1888. derial No. 294,977. (No model.)Patented in Denmark April 20, 1886, N0. 47 i, and in N01- Way October22, 1837,1lo. 724.

To [LZZ HF/11,0711 it may 0011100771,.

lie it known that l, CIu-us'rIaN FREDERIK llILKIEn, oi. Copenhagen, inthe Kingdom of Denmark, have in vented certain new and usefulImprovmnents in 'ilhermostats and Thermostatic Contact .l)evices, (forwhich I have received Letters Patent in Denmark April 2i), 18%, No.slT-l, and in Norway October 22, lShT, No. 724;) and I do hereby declarethe following to be a full, clear, and exact description of theinvention, such as will enable those skilled in the art to which itappertains to make and use the same.

)lyinvention relates to the general class of thermostat s, but is moreparticularly designed for use as an electrical contact device opened orclosed by rise or fall of temperature, according to the nature of itsintended use.

The invention consists in the construction. oi. the thermostat, and inthe combination and arrangement of parts, substantially as hereinafterfully described and claimed.

in the accompanying drawings, which form part of this specification,Figure l. is a plan view of the thermostat alone. Figs. 2 and 3 aresectional views of two different forms of the thermostat, the former tooperate by rise and the latter by fall of the temperature. lfiig. l is asectional. elevation, and Fig. 5 is a plan, of the thermostat andcontact-making device complete for indicating electrically a rise intemperature. Fig. 6 is a sectional view, on a larger scale, of thecomplete device for electrically indicating a fall in temperature. Fig.7 is a section, and Fig. 8 an elevation, of the thermostat andpush-button combined. Fig. ll is a se tion showing a thermostat locatedwithin the cover of a push-button. Figs. 10 and 12 are side elevationsof sin'ipler contact arrangements. Figs. 11 and ii are details.

In its simplest [form my improved thermostat consists of ahcrmetically-sealed flat case or chamber composed of a sheet-metalfront, a, and sheet-metal back I), soldered together at the edge, and astem or filling-tube, c. The back I) is dished to form the chamber. The

iront a is made of spring metal, for which purpose I prefer thinlmrd-rolled silver, both on account of its high thermal conductivity andbecause it is well adapted to resist oxidation by the contained fluid.It is bulged lorcibly inward or outward, according to its intended userespectively as amaximum or minimum temperature indicator. The inclosedchamber is filled according to requirement entirely or partly with asuitable fluid, which has its boiling-point or point of ebullition atthe temperature at which the contact is to be made. An excellent fluid,which allows a predetermined zuljustment of the apparatus to anytemperature between O and 100 centigrade, is ammoniawater.

After filling, the tube 0 is pinched together and soldered, and forconvenience l prei'er to solder to it a wire, d, for convenience ofconnection to the binding-screw e of the bedplate f. The bed-plate f hasa recess, y, under the thermostat, and into this extends a metal strip,71/, having a contact-point, 1', the strip 7: being connected to theother bindingpost, is. Recess g is entirely covered by the thermostat,and hence no dust or dirt can obtain access to foulthecontact-s11rfaces, which therefore will be always reliable, no matterhow dirty or dusty the fixture itself may become from the circumstancesof use or location.

As a maxiInum-indimtor, the device in iilling is arranged with theresilientcentcr oi. the front a bulged imvardly at temperatures belowthe maximum determined on, as in Figs. 2 and l, and when the temperaturerises the contained fluid expands and forces the concave front aoutwardly. As the latter passes the normal plane, it snaps outwardlypast such normal plane by its own resiliency, and thus altords a meansof effecting a good firm contact.

As a minimum-temperature indicator, on the other hand, the device infilling is so arranged that the resilient or spring center of the front(1 bulges outwardly at temperatures above the predetermined point, andthe attainment by the fluid in the chamber of that temperature causes itto sufficiently contract to permit the flattening ot' the convex fronta, which thereupon snaps inwardly beyond the normal plane, in a mannersimilar to that previously described. This resilient or snapping actionis peculiar and important, being sudden and affording a most reliablemovement for effecting contact, and gives a compartively wide range ofadjustment. Of course in the case just described the contacts will bearranged so as to be closed upon the inward movement of the spring-fronta.

By these two modifications of form I am able to construct the thermostatto fill any of the requirements for which thermostats may be wanted.

If the apparatus is to be used both as thermostat and push-button, it ismodified into the form shown at Figs. 7 and 8, where the front a, whileof larger size, is shaped as before; but the sheet-metal back I) isdeepened and provided with button or projection m, so that pressure uponthe latter bends in the back I) and causes the front a to act as if thecontained fluid had expanded.

The modified push-button and thermostat shown in Fig. 9 is intended forthe convenient stowage of the thermostat in rooms and other places whereit is not to be seen. The cover 12 not only hides it from view, but alsoprotects it from dust and unauthorized meddling. The one cover 1)incloses the push-button g and the thermostat a b, and the circuit isarranged so that either may effect a closure.

Obviously the thermostat may be made with both its back and frontresilient, or so that both may participate in the expansive orcontractile movement imparted by the contained fluid. The mereperipheral shape is unimportant; but I prefer the circular-disk formshown as being the cheapest and simplest.

, Two simple, practical, and cheap modifications are shown byFigs. 10and 12, and 11 and 13, respectively. In Figs. 10 and 12 I take two ofthe thermostatic disks (1 I), each having, besides its filling-tube c, arod, 1', fixed to it. The two are laid with their fronts a facing, andare tied or bound together after interposing between them aninsulating-disk, .9, having its center portion cutout, as shown in Fig.11. Increase of temperature causes the normally-inwardly bulged fronts ato expand outwardly and firmly snap into contact, thus closing thecircuit. In Fig. 12 but one thermostatic disk a Z) is employed, havingtube 0 Facing the front a. is a contactand rod r.

plate, t, Fig. 13, mounted on a bar, 1), and the whole bound togetherwith the insulatingdisk s between, as before.

The peculiar actionof the movable side of the thermostat possesses twoadvantages. In the first place, as has already been described, thebulged metal receives a motion far in excess of what it would receivewere it not for the particular construction whereby its own elasticitycarries it to a point beyond the normal plane. This motion occurs with asudden snap, owing to the construction, and gives a sharp sound, whichisquite loud, and in this respect the sound serves as a means of detectinga faulty contact in testing the instruments.

I am well aware that it is notnew to construct a thermostat of twoplates of metal in the form of a box, nor is it new to construct such abox with one of its sides or faces convex or concave; but so far as I amaware it has never heretofore been proposed to forci-- bly bulge one ofthe faces in such manner as to make it resilient and impossible tomaintain in a normal plane, so that it must occupy a position to eitherone side or the other of such normal plane.

I claim as my invention 1. A thermostat comprising a metallichermetically-sealed chamber containing an expansive and contractilefluid, and having one or more of its walls constructed of spring metalhaving a portion thereof sprung out of its normal plane and adapted inoperation to spring past such normal plane in both directions,substantially as described.

2. A thermostat comprising a fiat diskshaped chamber hermeticallysealed, composed of a cup-shaped back and a flat front solderedtogether, the front being of spring metal, and having a portion thereofsprung out of its normal plane and adapted in operation to spring pastthe normal plane, substantially as described.

In witness whereof I have hereunto signed my name in the presence of twosubscribing witnesses.

CHRISTIAN FREDERIK HILlIlER.

itnesses:

S. BoRss, J. V. SCHMIDT.

